NEW DELHI — Days after pirates seized a Saudi-owned supertanker carrying more than $100 million worth of crude oil, the Indian Navy said on Wednesday that one of its warships fought a four-to-five-hour battle at sea with would-be hijackers in the Gulf of Aden, sinking one suspect vessel in flames and forcing the pirates to abandon a second as they fled at high speed.

The New York Times

The drama on the night-time waters of the Indian Ocean late Tuesday underscored the growing international concern at the audacity with which armed pirates, mostly based in Somalia, range across vast areas of the Indian Ocean and the Gulf of Aden, attacking at will.

In a statement on Wednesday, Cmdr. Nirad Kumar Sinha, a spokesman for the Indian Navy, said the INS Tabar, encountered a flotilla of three pirate vessels some 320 miles south west of the Omani coast in the Gulf of Aden on Tuesday evening. One ship was apparently a “mother ship” used by pirates to extend their range, with two speedboats in tow. The suspect vessel matched the description of a pirate vessel issued by international anti-piracy authorities, Commander Sinha said.

He said the ‘“whole operation lasted four to five hours” and was “the first such incident in which the Indian Navy sank the pirate’s mother ship.”

When the Indian vessel tried to halt the ship, he said, “the vessel’s threatening response was that she would blow up the naval warship if it closed her.”

“Pirates were seen roaming on the upper deck of this vessel with guns and rocket propelled grenade launchers. The vessel continued its threatening calls and subsequently fired upon INS Tabar. On being fired upon, INS Tabar retaliated in self defense and opened fire on the mother vessel,” Commander Sinha said..

“As a result of the firing by INS Tabar, fire broke out on the vessel and explosions were heard, possibly due to exploding ammunition that was stored on the vessel. Almost simultaneously, two speedboats were observed breaking off to escape. The ship chased the first boat which was later found abandoned. The other boat made good its escape into darkness,” he said.

The Indian account suggested that pirates had attacked the Tabar, deployed to repulse pirates — equalling the brazenness of the hijacking on Sunday of the Sirius Star, a 1,080-foot supertanker with 25 crew on board.

At least eight ships have been hijacked in a vast expanse of ocean off east Africa in the past two weeks.

On the same day the Indian Navy engaged the pirates, a cargo ship registered in Hong Kong and loaded with 36,000 tons of wheat was seized in the Gulf of Aden, the official Chinese news agency Xinhua reported. The vessel, with 25 crew aboard, was headed for the Iranian port of Bandar Abbas.

That hijacking was followed by a report Wednesday, still to be confirmed by Greek authorities, that a Greek bulk carrier had also been seized in the Gulf of Aden. A regional maritime group based in Mombasa, Kenya, told Reuters 23 to 25 crew were aboard that ship. The Associated Press also reported that a Thai fishing boat with 16 crew members had been seized off the coast of Somalia on Tuesday.

International anti-piracy patrols, deployed since August, have had some success.

Last week, a British frigate, the Cumberland, launched speed-boats to intercept a hijacked dhow, exchanging fire with pirates before British naval personnel boarded it, the British Ministry of Defense said Tuesday. Eight alleged hijackers were captured and handed over to Kenyan authorities on Tuesday. Two people believed to be Somali nationals were killed in the operation, the ministry said.

On Wednesday, the fate of the supertanker Sirius Star, now anchored off the coast of Somalia, remained unclear. The ship’s owner said Tuesday it was working to free the 25-member crew. By Wednesday, there had been no reports that the hijackers had made known ransom demands.

The owner, Vela International, a subsidiary of the Saudi Arabia-based oil giant Saudi Aramco, said in a statement on Tuesday that the company was awaiting further contact from the pirates who seized the vessel about 480 miles off the coast of Somalia.The supertanker, about the same length as an AmericanNimitz class aircraft carrier, is the largest ship known to have been seized by pirates, and it was fully loaded with two million barrels of oil.

The crew members are citizens of Britain, Poland, Croatia, the Philippines and Saudi Arabia.

Lt. Nathan Christensen, deputy spokesman for the United States Fifth Fleet, said that the tanker had been anchored within sight of the coastal town of Xarardheere, 260 miles north of Mogadishu, the Somali capital, and part of a region known as a pirates’ sanctuary. .

While most of the hijackings have taken place in the Gulf of Aden, which separates Somalia from Yemen, the Saudi tanker was seized hundreds of miles to the south in open ocean as it headed toward the Cape of Good Hope.

“It is the first attack of its kind in which such a big vessel has been hijacked so far away from the coast,” said Cyrus Mody, of the International Maritime Bureau, which monitors global piracy. “It shows that the pirates now have the capability and capacity to sustain themselves in deep sea until the vessel actually comes by.” .

This year, at least 92 ships have been attacked in and around the Gulf of Aden, more than triple the number in 2007, according to the International Maritime Bureau At least 14 of those ships, carrying more than 250 crew members, are still in the control of hijackers.

An estimated $25 million to $30 million has been paid in ransom to Somali pirates this year, according to a report released Tuesday by Ban Ki-moon, the United Nations secretary general. He said that piracy was weakening the Somali government, which has been outgunned and outmaneuvered by the agile pirates.

Many of the captured ships sit a few miles off a 230-mile stretch of Somali coastline between Xarardheere and the town of Eyl, residents of the towns say. A Ukrainian vessel that was hijacked in September, loaded with tanks and other military equipment and weapons, is not far from the Saudi tanker.

Multinational naval vessels have thwarted two dozen attacks since August. But the area includes 2.5 million square miles of sea, “and we can’t be everywhere at once,” said Lieutenant Christensen of the Fifth Fleet.

Hari Kumar reported from New Delhi. Alan Cowell contributed from Paris, Mark McDonald from Hong Kong and Sharon Otterman from New York.